Drill bit with driven auxiliary bit



March 17, 1959 H. M. CAMERON ETAL 2,877,988

DRILL BIT WITH DRIVEN AUXILIARY BIT I Filed May '5, 1957 INVENTOR5 vHarrg M, Carney-on. BYEU9 55, LUcudAlei fi y M ATTORN 5 M L-W FE.

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United States Patent i American Coldset Corporation, Paterson, N. J., acorporation of New Jersey Application May 3, 1957, Serial No. 656,963 6Claims. (or. 255-401 This invention relates to rock drill bits and morepa ticularly to diamond drill bits of this character intended to providea substantial velocity to all of the abrading surfaces with respect tothe rock surfaces theyare intended to cut as by providing a positivelydriven auxiliary drill bit within a main drill bit body. I a I c I Inconventional drill bits, the cuttin'g v eloci ty of each diamond in thedrilling surface is directly proportional to the radius at which it ispositioned so that at zero radius, normally the axis of the drill, thevelocity is also zero and little, if any, cutting occurs.

Objects and features of this in'veritionare the provision of drill bitconstruction intended to provide substantial cutting velocities todiamonds at all radial positions relative toith'e of the main drill bit.a I I In an embodiment of the invention as herein contemplated; this isaccomplished by incorporatingan auxiliary drill bit in the main drillbit body whose Cutting surface protrudes slightly from the cuttingsurface of the main drill bit to compensate for wear and manufacturingtolerances under action of a Belleville or rinfg spring whosethrust isequivalent to the minimum thrust desired in a single bit of equivalentdiameter. This auxil'iary bit is keyed to a pinion which engagesa ringgearcar'ried by a free sleeve surrounding the main drill bit. A seriesof star wheels mounted on the sleeve serve to' cut keyway intothe wallof the hole b eifig dlil i d and to prevent rotation of the sleeve andalso of the ring. gear. In

consequence, rotation of the main drill body by the drill string causespositive rotation of the pinion and of. the auxiliary drill bit inopposite direction to rotation of the i n Preferably the diameter of theauxiliary drill bit; is in excess of the radius of the main drill bit sothat diamonds in the. auxiliary bit lying at the geometric center of themain drill bit have a positiv'e velocity imparted to them duringdrilling operations by reason of the positive rotation given to theauxiliary drillbit and also because of the eccentricity of the .axisofthe latter relative to the main drill bit. Thus drilling of the hole isspeeded because positive cutting action of andiamonds occurs. I

Additional objectsand features of the inventionare the provision ofcombined main and auxiliary drill bits in a unitary structure that issimple in structure; assembly, installation and operation. H

Further objects and features of th'e invention are the provision ofappropriate distributing passageways for water to'both the main andauxiliary bit surfaces to promote efficient chip removal and heatdissipation and also the provision of additional passageways open tq themain water passageway to provide water pressure to counter low pressuresof rock laden return mud and substantially preclude chances of seriousjamming of the gears by rock particles in this mud.

Other objects and features of this invention will becomeapparent fromthe following specification and the accompanying drawings wherein:

2,877,988 I Patented Mar. 17, 1959 ice Figure l is a longitudinalsection of a device embodying the invention taken along line 11 ofFigure 4; I Figure 2 is a transverse section taken along line 22 ofFigure Figure 3 is a transverse section taken along line 33 of Figure 1;and

Figure 4 is a bottom end elevation of the device.

Referring to the drawing, the reference character 10 generally denotes arock drilling bit embodying the invention. This bit 10 includes a mainbit body 11 which is threadedly engaged at 12 with an attaching shank 13whose outer end 14 is threaded for conventional attachment to a drillstring (not shown).

The bit body 11 and its shank 13 respectively in their upper and lowerportions are surrounded by an annular sleeve 15 which freely isrotatable relative to bothv as on thrustand radial ball bearings 16.Other types of bearings may be used. Longitudinal extending slots orgrooves 17 are provided at equi-spaced positions on, the periphery ofthe sleeve 15 and each serves to receive a series of rotatable starwheels 18, 19, 20 respectively supported on the shafts 21, 22 and 23which transversely span the slots or grooves 17. The star wheels 18, 19and 20" each project outwardly of theperipheral surface of the sleeve 15but are of progressively decreasing diameter downwardly for purposespresently to be described.

A ring gear 24 is fixedly supported in a recess 25 provided at one endof the sleeve 15 for purposes presently is be described.

Diamond abrading surfaces 26 and 27 of conventional types are providedat the drilling end of main bit body 11'. Grooves 28 and 29 in thesesurfaces communicate with water passageway 30 in the bit body 11. Thispassageway 30 in turn is in communication with the main water passageway31 inthe shank 13 to provide for flushing out of cut rock particles andfor heat dissipation.

The main bit body 11 is provided with a longitudinally extending recess32 located eccentri cally relative to its axis or center for receivingan auxiliary drill bit body 33. This auxiliary bit body 33 is supportedwithin the recess 32 as by the radial and thrust anti-friction ballbearings 34 and 35 and the nut 36 which threa dedl y engages the innerthreaded end 37 arms shaft portion 38 of the auxiliary bit body 33.Other types of bearings maybe used. The outer end portions of the body33 are provided with an abrading surface 39 which isspr'ing loadedaxially and maintained slightly protrudant as at the distance d belowthe lower abradingsurface 26 of the main bit body 11 as by aconventional Belleville or ring type spring 40 in order to compensatefor bearing and diamond means and manufacturing tolerances.

A gear 41 is keyed to shaft portion 38 of auxiliary bit body 33 andmeshes with the sleeve mounted ring gear 24 so that positive drive willbe irnpartedto the gear 41 and consequently to auxiliary bit 33 whenring gear 24 is held against rotation during driven rotation of the mainbit body 11 as will be presently described. I v

The abrading surface 39 of auxiliary bit body 32 is grooved at 42. Thesegrooves communicate with a water passageway 43 which in turn is in opencommunication with main water passageway 31 in the shank 13for particleflushing and for heat dissipation. I

The auxiliary drill bit 33 at its abrading surface 39 overlaps thegeometric center of the main bit body so that rotation of the main andauxiliary drill bit bodies will provide a substantial cutting velocityto the abrading surfaces even at the geometric center of the main bitbody.

For ease of assembly 'of the component parts of the main and auxiliarydrill bits, the main drill bit body 11 and its shank 13 are separatebeing joined at'tlie threaded joint 12 so that the auxiliary bit body 33may be secured in the main bit body 11 by the nut 36 prior to thethreaded joining at 12 of the main bit body 11 and its shank portion 13.Once joined, radial pins 44 serve to prevent unscrewing ofthe partsatsaid threaded joint 1-2. Also the ring gear 24 for assembly isconstructed in sections and secured to the sleeve as by bolts or pins45.

Additional fluid passageways 46 extending radially from the main waterpassageway 31 into the star wheel containing grooves or recesses 17 andadditional fluid passageways 47 extending from fluid passageway 30 tothe chamber 32 containing the gears 24 and 41 provide pressurized areasinto which rock laden return mud incidental to drilling and which isunder low pressure cannot enter. Thus chances of jamming the gears byrock particles is minimized.

In operation, after attachment of shank 13 to the drill string (notshown) when the drill assembly described is lowered into the hole andthe drill string is rotated the drill bits cut the hole. As the drillassembly moves down into the hole drilled, the star wheels cutlongitudinal key- .ways K into the hole wall. The progressivelyincreasing the sleeve 15 and consequently of the ring gear 24 which issecured to this sleeve. In consequence the further rotation of the drillstring causes driven drilling rotation of the main drill body 11 andforces rotation of gear 41 and rotation of auxiliary drill bit 33 inopposite direction to the direction of rotation of the main drill bitbody 11. 7

Although star wheels have been described as a means for preventingrotation of the sleeve 15, other appropriate means may be utilized. Asan alternative solid metal inserts may be carried in the groove theiroutwardly projecting surfaces being shaped to effect breaching of akeyway inthe wall. Other means of preventing rotation of the sleeve 15while permitting free vertical motion thereof likewise are possible andare contemplated.

An additional feature of note is that the diameter of the auxiliarybitneed not exceed the radius of the main drill bit. It is sulficient ifits periphery overlaps the center line of the main bit and for thispurpose its diameter can have any selected value either less than or inexcess of the main bit radius,

While a specific embodiment of the invention has been shown anddescribed, variations in structural detail within the scope of theappended claims are possible and are contemplated. There is no intentiontherefore of limitation to the exact details shown and described.

What is claimed is:

1. In combination, a main drill bit having an abrading surface, arotatable auxiliary drill bit having an abrading surface, means forsupporting said auxiliary drill bit within said main drill bit wherebyits arbading surface will operate generally within the plane of saidabrading surface of said main drill bit, a rotatable sleeve carried bysaid main drill bit, means for rotatably connecting said sleeve to saidmain drill bit, a ring gear secured to said sleeve, a pinion meshingwith said ring gear and keyed to said rotatable auxiliary drill bit, andmeans extending from said sleeve for engaging the wall of a hole beingdrilled to prevent rotation of said sleeve and ring gear during drillingrotation of said main drill bit and thereby cause positive rotation ofthe pinion and of the auxiliary drill bit.

2. In combination, a main drill bit having an abrading surface, arotatable auxiliary drill bit, having an abrading surface, bearing meansfor supporting the auxiliary drill bit within said main drill bitwhereby the said abrading surfaces will operate generally within thesame plane, a rotatable sleeve carried by said main drill bit, means forrotatably connecting said sleeve to said main drill bit, a ring gearsecured to said sleeve, a pinion keyed to said auxiliary drill bit andmeshing with said ring gear, star wheel means mounted on said sleeve andprojecting outwardly of its periphery for engaging the wall of a holebeing drilled and cutting a keyway therein, engagement of said starwheels in the keyway preventing rotation of said sleeve and ring gearduring drilling rotation of said main drill bit and thereby causingpositive rotation of the pinion and auxiliary drill bit in oppositedirection to the rotary direction of the main drill bit.

3. In combination, a main drill bit having an abrading surface, arotatable auxiliary drill bit having an abrading surface, means forsupporting said auxiliary drill bit within said main drill bit wherebyits abrading surface will operate generally within the plane of saidabrading surface of said main drill bit, a rotatable sleeve carried bysaid main drill bit, means for rotatably connecting said sleeve to saidmain drill bit, a ring gear secured to said sleeve, a pinion meshingwith said ring gear and keyed to said rotatable auxiliary drill bit,means extending from said sleeve for cutting a ,keyway into the wall ofa hole being drilled and to prevent rotation of said sleeve and ringgear during drilling rotation of said main drill bit, thereby causingpositive oppositely directed drilling rotation to said auxiliary. drillbit, and said bits having passages for distributionof water to theirdrilling surfaces and the said ring'gear for prevention of jamming ofsaid gear and pinion by rock particles in rock laden return mud from thehole.

' 4. In combination with a rotary drill string, a mam drill bitconnected to said drill string and having an abrading surface, a freesleeve annularly disposed around said main drill bit, means forrotatably connecting said free sleeve to said main drill bit, a ringgear interior of said free sleeve. and attached thereto, a rotatableauxiliary bit having an abrading surface, means for supporting saidauxiliary drill bit within said main drill bit whereby its abradingsurface operates generally within the plane of said abrading surface of.the main drill bit, a pinion attached to said auxiliary drill bit andmeshing with said ring gear, spring means between said auxiliary drillbit and said main drill bit for assuring a minimum of positive downwardthrust of said auxiliary drill bit, and means extending outwardly ofsaid free sleeve and connected thereto for engaging a wall portion of ahole being drilled to prevent rotation of said free sleeve and said ringgear during drilling rotation of said main drill bit and thereby causepositive rotation of said pinion and of said auxiliary drill bit.

5. In combination with a rotary drill string, a main drill bit connectedto said drill string and having an abrading surface, a free sleeveannularly disposed around said main .drillbit, means for rotatablyconnecting said free sleeve to said main drill bit, a ring gearinterior. of said free sleeve and attached thereto, a rotatableauxiliary bit having an abrading surface, means for supporting saidauxiliary drill bit within said main drill bit whereby its abradingsurface operates generally within the plane of said abrading surface ofthe main drill bit, a pinion attached to said auxiliary drill bit andmeshing with said ring gear, spring means between said auxiliary drillbit and-said main drill bit for assuring a minimum of positive downwardthrust of said auxiliary drill bit, and star wheel means mounted on saidfree sleeve to project outwardly therefrom for engaging a wall portionof a hole being drilled to prevent rotation of said free sleeve and saidring gear during drilling rotation of said main drill bit and therebycause positive rotation of said pinion and of said auxiliary drill bit.

6. In combination with a rotary drill string, a main drill bit connectedto said drill string and having an abrading surface, a free sleeveannularly disposed around said main drill bit, means for rotatablyconnecting said free sleeve to said main drill bit, a ring gear interiorof said free sleeve and attached thereto, a rotatable auxiliary bit .5abrading surface operates generally within the plane of said abradingsurface of the main drill bit, a pinion attached to said auxiliary drillbit and meshing with said ring gear, spring means between said auxiliarydrill bit and said main drill bit for assuring a minimum of positivedownward thrust of said auxiliary drill bit, and means extendingoutwardly of said free sleeve and connected thereto for engaging a wallportion of a hole being drilled to prevent rotation of said free sleeveand said ring gear during drilling rotation of said main drill bit andthereby cause positive rotation of said pinion and of said auxiliary 6drill bit, both the said drill bits having passages for distribution ofdrilling fluid to their said abrading surfaces, and the said main drillbit having passages to said means connected thereto and to said ringgear for distribution 5 of drilling fluid thereto.

References Cited in the file of this patent UNITED STATES PATENTSAdamson June 20, 1950 2,667,334 Ortloif Jan. 26, 1954

